Latch mechanisms

Abstract

A latch bolt assembly and a locking device for use in a latch mechanism which can be fitted to a door or the like. The latch bolt assembly includes a casing and a bolt device which is receivable within a guide passage in the casing for movement between latched and retracted positions. A biasing spring is disposed between co-operating stops on the casing and the bolt device so as to normally urge the bolt device towards the latched position. The locking device comprises a locking element movable between a lock position and a release position and a control member which controls movement of the locking element and an actuating member which causes movement of the control member.

We claim: 
     
       1. A locking device for a latch mechanism, the latch mechanism including a bolt device movable between a latched position and retracted position, an actuator shaft operatively connected to the bolt device such that rotation thereof about an axis of rotation causes movement of the belt device between the latched and retracted positions and at least one handle operatively connected to the actuator shaft by which the actuator shaft can be rotated, the locking device comprising: a locking element mounted for movement in the direction of the axis of the actuator shaft between a lock position in which rotation of the actuator shaft by the handle is inhibited and a release position in which the actuator can be rotated by the handle;   a control member operatively connected to or engageable with said locking element said control member being mounted for movement in the direction of the actuator shaft between first and second positions whereby in said first position the locking element is caused to adopt the lock position and in said second position the locking element can adopt the release position, whereby in said first position the control member is capable of rotatable movement and in said second position is inhibited from that rotational movement; and   an actuating member operable to cause the axial movement of the control member and drive means associated with said actuating member and said control member for causing rotation of the control member when in the first position.   
     
     
       2. A locking device according to claim 1 further including a support body operatively connected to the actuator shaft said support body being adapted to support at least part of said locking element and said control member and permit movement therealong in the direction of the axis of the actuator shaft. 
     
     
       3. A locking device according to claim 2 wherein said support body operatively connects said actuator shaft to said handle. 
     
     
       4. A locking device according to claim 3 wherein said support body comprises a tubular or rod like member operatively connected to one end of the actuator shaft. 
     
     
       5. A locking device according to claim 1 wherein said locking element includes a first part which includes one or more segments which in the lock position adapted to engage a stop to inhibit rotation of the actuator shaft and a pair of arms which are operatively connected to a second part which comprises a ring like element slidable along the support body. 
     
     
       6. A locking device according to claim 1 wherein said control member comprises an annular disc-like member receivable on the support body for movement therealong. 
     
     
       7. A locking device according to claim 6 wherein said drive means comprises a plurality of ratchet elements and the disc-like member engageable by projections on said actuator. 
     
     
       8. A locking device according to claim 1 wherein said actuator comprises a manually depressible button. 
     
     
       9. A locking device according to claim 1 further including biasing means urging said locking element into said release position.